- Email: [email protected]
A weightbearing technique for the measurement of ankle joint dorsiflexion with the knee extended is reliable
Journal of Science and Medicine in Sport (2009) 12, 54—59
ORIGINAL PAPER
A weightbearing technique for the measurement of ankle joint dorsiflexion with the knee extended is reliable Shannon E. Munteanu a,b,∗, Andrea B. Strawhorn c, Karl B. Landorf a,b, Adam R. Bird a,b, George S. Murley a,b a
Department of Podiatry, Faculty of Health Sciences, La Trobe University, Australia Musculoskeletal Research Centre, Faculty of Health Sciences, La Trobe University, Australia c Corio Bay Sports Medicine Centre, Australia b
Received 11 April 2007 ; received in revised form 21 June 2007; accepted 24 June 2007 KEYWORDS Ankle joint; Reliability; Range of motion
Summary Measurement of ankle joint dorsiflexion is routinely undertaken by clinicians who manage lower limb musculoskeletal pathology. This study aimed to determine the reliability of a technique to measure ankle joint dorsiflexion in a weightbearing position with the knee extended. Four raters with varying clinical experience measured ankle joint dorsiflexion in a weightbearing position with the knee extended on 30 asymptomatic participants. Measurements occurred on two occasions, 1 week apart using (i) a digital inclinometer and (ii) a clear acrylic plate apparatus. Intraclass correlation coefficients (ICCs) and 95% limits of agreement (LOAs) were calculated. Intra-rater reliability of the experienced raters was high for both the digital inclinometer (average ICC = 0.88, average 95% LOA = −6.6◦ to 4.8◦ ) and the clear acrylic plate apparatus (average ICC = 0.89, average 95% LOA = −7.2◦ to 4.3◦ ). Intra-rater reliability of the inexperienced rater was good to high for both the digital inclinometer (ICC = 0.77, 95% LOA = −9.1◦ to 8.3◦ ) and the clear acrylic plate apparatus (ICC = 0.89, 95% LOA = −8.1◦ to 4.6◦ ). Inter-rater reliability was high for both the digital inclinometer (ICC = 0.95, 95% LOA = −5.7◦ to 5.7◦ ) and the clear acrylic plate apparatus (ICC = 0.97, 95% LOA = −4.7◦ to 4.7◦ ). Measurements of ankle dorsiflexion in a weightbearing position with the knee extended can be performed reliably by experienced and inexperienced raters. However, the reliability of this measurement technique needs to be interpreted in the context of the purpose for which the measurement is intended. © 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Introduction ∗
Corresponding author. E-mail address: [email protected] (S.E. Munteanu).
Ankle joint dorsiflexion is important to allow the body to progress forward over the weightbearing
1440-2440/$ — see front matter © 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.jsams.2007.06.009
Measurement of ankle dorsiflexion is reliable foot during gait and absorb impact force during ballistic activities such as jumping.1,2 Limited ankle joint dorsiflexion is commonly caused by tightness of soleus and gastrocnemius muscles,3,4 and has been shown to be a risk factor for and/or associated with several musculoskeletal pathologies of the foot including forefoot pain,3 plantar fasciitis5 and navicular stress fractures.6 Patella7 and Achilles tendinopathy,8 ankle sprains9 and lower limb overuse injuries in football players10 have also been shown to be caused by, or associated with limited ankle joint dorsiflexion. It is therefore important that clinicians who manage musculoskeletal pathology of the foot and lower limb are able to reliably assess ankle joint dorsiflexion range of motion. This would allow the practitioner to identify those at risk of developing foot and lower limb injuries, accurately measure the level of dysfunction post-injury and determine the effectiveness of an intervention aimed at improving ankle joint dorsiflexion range of motion. The measurement of ankle joint dorsiflexion has traditionally occurred with the patient in a non-weightbearing position.4 However, the reliability of this measurement technique is questionable (intra-rater reliability ICCs ranging from 0.64 to 0.99 and inter-rater ICCs ranging from 0.29 to 0.81).11 In light of the questionable reliability of non-weightbearing measurements of ankle joint dorsiflexion, an alternative weightbearing ‘lunge’ technique has been described.12 This measurement technique has been shown to be reliable (high intraand inter-rater reliability).12,13 However, a major limitation of this measurement technique is that it primarily assesses the role of the soleus muscle and joint capsule structures of the ankle joint as it is performed with a flexed knee.4 This measurement technique is unable to determine if tightness of the gastrocnemius muscle is a contributing factor to limited ankle joint dorsiflexion.4 One way to overcome this limitation would be to perform the measurement of ankle joint dorsiflexion range of motion in a weightbearing position with the knee extended. Only one study has investigated the reliability of the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended.14 Although the results showed high intrarater reliability (coefficient of variation of 2.5%), the inter-rater reliability was not reported. Furthermore, only experienced clinicians were used, so it is unknown if this measurement technique is reliable when inexperienced raters perform this measurement. Therefore, the aim of this study was to determine both the intra- and inter-rater reliability of
55 the measurement of ankle dorsiflexion in a weightbearing position with the knee extended, using both experienced and inexperienced raters.
Methods Participants Participants were recruited from a student population at a University. Thirty individuals (10 male, 20 female), aged 19—42 years (mean ± S.D., 22.1 ± 5.6), height (mean ± S.D.) 171.8 ± 8.9 cm, BMI (mean ± S.D.) 22.8 ± 3.3 were recruited. Participants were excluded if they had any acute or chronic lower limb pathology in the previous 12 months, previous history of surgery to the lower limbs or any neurological or balance deficits. Institutional ethics approval was granted prior to the study and all participants provided written informed consent.
Raters Four podiatrists were used as raters. Raters A—C had 3, 10 and 20 years of clinical experience, respectively. Rater D was a fourth year undergraduate podiatry student, considered to have minimal clinical experience. Prior to commencing data collection, all raters undertook two 15 min training sessions which allowed the raters to familiarise themselves with the measurement protocol and practice the measurement technique. The training sessions were separated by 3 days and the final session occurred 1 week prior to data collection.
Measurement technique The participant placed both hands on a wall in front of them. They positioned their right leg behind the left leg as far as possible ensuring the right knee was fully extended. The right foot was positioned parallel to a tape-line on the floor, which was orientated perpendicular to the wall. The second toe and the centre of the heel were placed directly over the tape-line in order to attempt to reduce the subtalar joint from pronating during the measurement procedure and therefore falsely elevating the value of ankle joint dorsiflexion.9 The participant then leaned forward until maximum stretch was felt in the right posterior leg, while keeping the right knee fully extended and the right heel in contact with the ground. The left leg remained in a comfortable position to maintain balance and not to restrict dorsiflexion of the right ankle. The angle
56 the right tibia made to the vertical was then measured using (i) a digital inclinometer and (ii) a clear acrylic plate apparatus. Digital inclinometer The rater aligned the digital inclinometer (Baseline® Digital Inclinometer 12-1057) so that it was positioned on a mark made on the mid-point of the anterior tibial border, between the tibial tuberosity and the anterior joint line of the ankle. Care was taken to ensure that the digital inclinometer was not positioned over the tibialis anterior muscle belly. To minimise rater bias, the face of the digital inclinometer was positioned away from the rater and the readings were recorded (in degrees) by an independent third person (Supplementary File 1). Clear acrylic plate apparatus A clear acrylic plate apparatus marked with 2◦ increments was used to measure ankle joint dorsiflexion.13 For each participant, two anatomical points were marked. Firstly, the lateral malleolus was identified and marked, being the axis of rotation of the ankle joint. Secondly, the head of the fibula was located and marked as the proximal landmark.13 The rater then positioned the clear acrylic plate apparatus perpendicular to the wall alongside the participant, ensuring the marking (on the bottom right corner) of the clear acrylic plate apparatus was bisecting the lateral malleolus. The participant then leaned forward and the position of the fibula head was marked on the clear acrylic plate apparatus with a nonpermanent marker (Supplementary File 2). The angle formed between the lateral malleolus and the fibula head relative to the vertical was recorded (in degrees) by an independent third person, who then removed the marking on the clear acrylic plate apparatus.
Procedure Participants initially sat for 5 min and then completed a series of pre-conditioning stretches of the gastrocnemius muscle prior to data collection.15,16 Each participant performed three, 30 s gastrocnemius muscle stretches of the right leg with a 10 s rest period between each stretch to pre-condition the gastrocnemius muscle as well as familiarise themselves with the measurement technique.16 After this pre-conditioning procedure, data collection began. The participant lay supine while the rater marked the anatomical landmarks on the participant’s right leg using a non-permanent
S.E. Munteanu et al. ink marker. Three anatomical landmarks were marked, the fibula head, the lateral malleolus13 and the mid-point of the anterior border of the tibia.12 The participants then assumed the extended knee weightbearing position described previously. The angle that the tibia made to the vertical was measured using (i) a digital inclinometer and (ii) the clear acrylic plate apparatus. The participant returned to the starting position to rest for 10 s and the measurement was repeated. The mean value of the two measurements for each measurement apparatus was documented and used for data analysis.13 Once the measurement procedure was performed by each rater, the ink markings were removed using alcohol wipes. The four raters each performed the measurement procedure within a 20 min period. The sequence of raters was randomised for both the test and retest sessions, as was the order of measurement apparatus used. Each participant returned after 7 days and the measurement protocol was repeated. A 1-week test—retest period was used as this testing interval was considered large enough to avoid fatigue, learning and memory effects, but small enough to avoid genuine changes in ankle joint range of motion.12
Statistical analysis Data from the right side only was used to satisfy the assumption of independence of data.17 Data was explored for normal distribution (Shapiro—Wilks test). A two-way repeated measures ANOVA was used to assess for systematic differences between repeated measures for each rater (two levels: test and retest sessions) and between raters (four levels: raters A—D). P-values less than 0.05 were considered significant. Post hoc comparisons were performed using Bonferroni-adjusted paired t-tests.18 To determine the intra-rater reliability for each rater, two approaches were used: intraclass correlation coefficients (ICCs) were calculated (model 2,2), as were standard error of measurement (S.E.M.) with 95% limits of agreement (95% LOAs).19 To determine the average intra-rater ICC for raters A—C (experienced clinicians); a form of standardised (z) score was used. Individual raters’ ICC (r) values were transformed to z-scores. The resulting z-scores were averaged and the average z-score was then transformed back into an r value.20 To determine the inter-rater reliability, ICCs (model 2,4) and mean S.E.M.s with 95% LOAs were calculated.21 A mean inter-rater 95% LOA was
Measurement of ankle dorsiflexion is reliable
57
derived from the average of the combinations of comparisons of raters A—D. Data from both the test and retest sessions were analysed.
Results Ankle joint dorsiflexion measured with a digital inclinometer The mean (range) values for each rater at the test and retest sessions are shown in Supplementary File 3. The main effect of session was not significant (F1 = 2.992, p = 0.09). Similarly, the main effect of rater was not significant (F3 = 2.470, p = 0.07). Clinically, these results suggest error associated with measurement between raters and between sessions was random and not a result of systematic differences. Intra- and inter-rater reliability of the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended is shown in Table 1. All three experienced raters (A—C) demonstrated high intra-rater reliability with ICCs between 0.85 and 0.91 and narrow 95% LOAs. The inexperienced rater (rater D) showed slightly less reliability with a lower ICC and wider 95% LOA. Table 1 also shows the ICCs (95% CI), S.E.M.s and 95% LOAs for the inter-rater reliability of both the test and retest sessions for all four raters. The reliability values for the test session were slightly greater than the retest session. However, the inter-rater reliability for both sessions was high, indicated by ICCs greater than 0.90 and narrow 95% LOAs.
Ankle joint dorsiflexion measured with a clear acrylic plate apparatus The mean ± S.D. (range) values for each rater at the test and retest session are shown in Supplementary File 3. The main effect of rater was not significant (F3 = 2.013, p = 0.12). However, the main effect of session was significant (F1 = 16.476, p < 0.001) revealing significant differences between the test and retest sessions for all raters except rater B. Intra- and inter-rater reliability of the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended using the clear acrylic plate apparatus is shown in Table 2. All raters, except rater B demonstrated high intrarater reliability with ICCs between 0.89 and 0.96 and narrow 95% LOAs. Rater B showed moderate reliability with ICCs considerably lower and 95% LOAs considerably wider than the other three raters (A, C and D). Table 2 also shows the ICCs (95% CI), S.E.M.s and 95% LOAs for the inter-rater reliability for the test and retest sessions of all four raters. The inter-rater reliability for both the test and retest sessions was high, with ICCs greater than 0.92 and narrow 95% LOAs.
Discussion This study has demonstrated that measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended can be performed reliably by experienced and inexperienced raters using both
Table 1 The intra- and inter-rater reliability for the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended using a digital inclinometer
Table 2 The intra- and inter-rater reliability for the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended using a clear acrylic plate apparatus
Rater
Rater
A B C Averagea D
Intra-rater reliability Type (2,2) ICC (95% CI)
S.E.M. (95% LOA) (◦ )
0.87 0.85 0.91 0.88 0.77
1.6 1.8 1.2 1.5 2.4
(0.72—0.94) (0.69—0.93) (0.81—0.96) (0.75—0.94) (0.52—0.89)
(−6.5 (−7.7 (−5.5 (−6.6 (−9.1
to to to to to
5.5) 5.6) 3.4) 4.8) 8.3)
A B C Averagea D
Inter-rater reliability Type (2,4) ICC S.E.M. (95% LOA) (95% CI) (◦ ) Test Retest a
0.95 (0.91—0.97) 0.92 (0.86—0.96)
z-Transformed data.
1.77 (−5.7 to 5.7) 2.05 (−6.3 to 6.3)
Intra-rater reliability Type (2,2) ICC (95% CI)
S.E.M. (95% LOA) (◦ )
0.96 0.67 0.90 0.89 0.89
1.0 2.5 1.3 1.6 1.7
(0.91—0.98) (0.34—0.85) (0.79—0.95) (0.76—0.95) (0.77—0.94)
(−5.2 to 2.4) (−10.0 to 7.3) (−6.5 to 3.1) (−7.2 to 4.3) (−8.1 to 4.6)
Inter-rater reliability Type (2,4) ICC S.E.M. (95% LOA) (95% CI) (◦ ) Test Retest a
0.97 (0.95—0.98) 0.93 (0.87—0.96)
z-Transformed data.
1.3 (−4.7 to 4.7) 1.8 (−6.2 to 6.2)
58 the digital inclinometer and the clear acrylic plate apparatus. These results are comparable to the findings from the study by Ekstrand et al.14 However, our study adds to the work of Ekstrand et al.14 as they assessed intra-rater reliability only and used experienced raters only. An issue to consider when interpreting the results of the present study was that one experienced rater showed considerably lower intra-rater reliability than the other raters when measuring ankle joint dorsiflexion using the clear acrylic plate apparatus. This technique (more so than the digital inclinometer) relies on the ability of the rater to palpate surface anatomical landmarks (such as the fibula head). Imprecision in locating and marking relevant anatomical locations could adversely affect the reliability of this technique. In order to interpret the reliability findings in a clinical context, 95% LOAs were determined.21 The 95% LOAs suggest that to attribute a difference in ankle joint dorsiflexion to a ‘true change/difference’ and not measurement error, the observed change/difference must be greater than 7◦ and 6◦ when performed by the same rater or different raters, respectively. Therefore, this measurement technique would be appropriate to use as a screening tool to determine those at risk of developing lower limb injuries, as there is a large range of ankle joint dorsiflexion values in the population (34◦ —60◦ ) and these differences do affect the risk of being injured.9 In contrast, this measurement technique may be inappropriate when used to assess for changes in ankle joint dorsiflexion range of motion resulting from a calf muscle stretching program in young, healthy people as only small changes in range of motion (∼2◦ —3◦ ) are expected.22 Although, the technique may be a useful outcome measure for stretching interventions in other clinical groups (such as older people or those with heel pain) where larger increases in ankle range of motion may be achieved.23,24 The results of this study need to be interpreted in the context of its limitations. One limitation of weightbearing measurements of ankle joint dorsiflexion is that they are unlikely to be a true measure of dorsiflexion occurring solely at the ankle joint but instead, provide a cumulative measure of motion available at the talocrural, subtalar and tarsal joints.12 Indeed, a more pronated foot posture has been shown to be positively correlated to the ankle joint weightbearing lunge.25 In addition, the findings regarding the inexperienced rater need to be interpreted with caution since only one inexperienced rater was used which makes it difficult to make generalised comments about inexperienced raters. Finally, the results of this study
S.E. Munteanu et al. cannot be extrapolated to patients with lower limb pathology or those outside the age range of 18—42 years. As health practitioners are more likely to treat symptomatic individuals of all ages, further research needs to be done to determine the reliability of the weightbearing measurement of ankle joint dorsiflexion with the knee extended in these populations.
Practical implications • Measurements of ankle joint dorsiflexion with participants in a weightbearing position with the knee extended are reliable when performed by the same rater or by different raters. • The reliability of measurements of ankle joint dorsiflexion are not strongly affected by the experience of the rater or the equipment used.
Supplementary Files Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jsams.2007.06.009.
References 1. Kaufman KR, Sutherland D. Kinematics of normal human walking. In: Rose J, Gamble JG, editors. Human walking. 3rd ed. Philadelphia, USA: Lippincott Williams and Wilkins; 2006 [Chapter 3]. 2. Prilutsky BI, Zatsiorsky VM. Tendon action of twojoint muscles: transfer of mechanical energy between joints during jumping, landing, and running. J Biomech 1994;27(1):25—34. 3. DiGiovanni CW, Kuo R, Tejwani N, Price R, Hansen Jr ST, Cziernecki J, et al. Isolated gastrocnemius tightness. J Bone Joint Surg 2002;84-A(6):962—70. 4. Root ML, Orien WP, Weed JH. Motion at the joints of the foot. Normal and abnormal function of the foot. 1st ed. Los Angeles, CA, USA: Clinical Biomechanics Corporation; 1977 [Chapter 1]. 5. Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for plantar fasciitis: a matched case-control study. J Bone Joint Surg Am 2003;85-A(5):872—7. 6. Agosta J, Morarty R. Biomechanical analysis of athletes with stress fractures of the tarsal navicular bone: a pilot study. Aust J Podiatr Med 1999;33(1):13—8. 7. Malliaras P, Cook JL, Kent P. Reduced ankle dorsiflexion range may increase the risk of patella tendon injury among volleyball players. J Sci Med Sport 2006;9(4):304—9. 8. Kaufman KR, Brodine SK, Shaffer RA, Johnson CW, Cullison TR. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med 1999;27(5):585—93.
Measurement of ankle dorsiflexion is reliable 9. Pope R, Herbert R, Kirwan J. Effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Aust J Physiother 1998;44(3):165—72. 10. Gabbe BJ, Finch CF, Wajswelner H, Bennell KL. Predictors of lower extremity injuries at the community level of Australian football. Clin J Sports Med 2004;14(2):56—63. 11. Martin RL, McPoil TG. Reliability of ankle goniometric measurements: a literature review. J Am Podiatr Med Assoc 2005;95(6):564—72. 12. Bennell KL, Talbot R, Wajswelner H, Techovanich W, Kelly DH, Hall AJ. Intra-rater and inter-rater reliability of a weight-bearing lunge measure of ankle dorsiflexion. Aust J Physiother 1998;44(3):175—9. 13. Menz HB, Tiedemann A, Kwan MM, Latt MD, Sherrington C, Lord SR. Reliability of clinical tests of foot and ankle characteristics in older people. J Am Podiatr Med Assoc 2003;93(5):380—7. 14. Ekstrand J, Wiktorsson M, Oberg B, Gillquist J. Lower extremity goniometric measurements: a study to determine their reliability. Arch Phys Med Rehab 1982;63(4):171—5. 15. Kilgour G, McNair P, Stott NS. Intrarater reliability of lower limb sagittal range-of-motion measures in children with spastic diplegia. Dev Med Child Neurol 2003;45(6):391—9. 16. Zito M, Driver D, Parker C, Bohannon R. Lasting effects of one bout of two 15-second passive stretches on ankle dorsiflexion range of motion. J Orthop Sports Phys Ther 1997;26(4):214—21. 17. Menz HB. Two feet, or one person? Problems associated with statistical analysis of paired data in foot and ankle medicine. Foot 2004;14(1):2—5.
59 18. Portney LG, Watkins MP. Multiple comparison tests. Foundations of clinical research: applications to practice. 2nd ed. NJ, USA: Prentice-Hall, Inc.; 2000 [Chapter 21]. 19. Portney LG, Watkins MP. Statistical measures of reliability. Foundations of clinical research: applications to practice. 2nd ed. NJ, USA: Prentice-Hall, Inc.; 2000 [Chapter 26]. 20. Evans AM, Copper AW, Scharfbillig RW, Scutter SD, Williams MT. Reliability of the foot posture index and traditional measures of foot position. J Am Podiatr Med Assoc 2003;93(3):203—13. 21. Bland JM, Altman DG. Measuring agreement in method comparison studies. Stat Methods Med Res 1999;8(2): 135—60. 22. Radford JA, Burns J, Buchbinder R, Landorf KB, Cook C. Does stretching increase ankle dorsiflexion range of motion? A systematic review. Br J Sports Med 2006;40(10): 870—5. 23. Gajdosik RL, Vander Linden DW, McNair PJ, Williams AK, Riggin TJ. Effects of an eight-week stretching program on the passive-elastic properties and function of the calf muscles of older women. Clin Biomech 2005;20(9): 973—83. 24. Porter D, Barrill E, Oneacre K, May BD. The effects of duration and frequency of Achilles tendon stretching on dorsiflexion and outcome in painful heel syndrome: a randomised, blinded, control study. Foot Ankle Int 2002;23(7):619—24. 25. Burns J, Crosbie J. Weightbearing ankle dorsiflexion range of motion in idiopathic pes cavus compared to normal and pes cavus feet. Foot 2005;15(2):91—4.
Available online at www.sciencedirect.com
ORIGINAL PAPER
A weightbearing technique for the measurement of ankle joint dorsiflexion with the knee extended is reliable Shannon E. Munteanu a,b,∗, Andrea B. Strawhorn c, Karl B. Landorf a,b, Adam R. Bird a,b, George S. Murley a,b a
Department of Podiatry, Faculty of Health Sciences, La Trobe University, Australia Musculoskeletal Research Centre, Faculty of Health Sciences, La Trobe University, Australia c Corio Bay Sports Medicine Centre, Australia b
Received 11 April 2007 ; received in revised form 21 June 2007; accepted 24 June 2007 KEYWORDS Ankle joint; Reliability; Range of motion
Summary Measurement of ankle joint dorsiflexion is routinely undertaken by clinicians who manage lower limb musculoskeletal pathology. This study aimed to determine the reliability of a technique to measure ankle joint dorsiflexion in a weightbearing position with the knee extended. Four raters with varying clinical experience measured ankle joint dorsiflexion in a weightbearing position with the knee extended on 30 asymptomatic participants. Measurements occurred on two occasions, 1 week apart using (i) a digital inclinometer and (ii) a clear acrylic plate apparatus. Intraclass correlation coefficients (ICCs) and 95% limits of agreement (LOAs) were calculated. Intra-rater reliability of the experienced raters was high for both the digital inclinometer (average ICC = 0.88, average 95% LOA = −6.6◦ to 4.8◦ ) and the clear acrylic plate apparatus (average ICC = 0.89, average 95% LOA = −7.2◦ to 4.3◦ ). Intra-rater reliability of the inexperienced rater was good to high for both the digital inclinometer (ICC = 0.77, 95% LOA = −9.1◦ to 8.3◦ ) and the clear acrylic plate apparatus (ICC = 0.89, 95% LOA = −8.1◦ to 4.6◦ ). Inter-rater reliability was high for both the digital inclinometer (ICC = 0.95, 95% LOA = −5.7◦ to 5.7◦ ) and the clear acrylic plate apparatus (ICC = 0.97, 95% LOA = −4.7◦ to 4.7◦ ). Measurements of ankle dorsiflexion in a weightbearing position with the knee extended can be performed reliably by experienced and inexperienced raters. However, the reliability of this measurement technique needs to be interpreted in the context of the purpose for which the measurement is intended. © 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Introduction ∗
Corresponding author. E-mail address: [email protected] (S.E. Munteanu).
Ankle joint dorsiflexion is important to allow the body to progress forward over the weightbearing
1440-2440/$ — see front matter © 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.jsams.2007.06.009
Measurement of ankle dorsiflexion is reliable foot during gait and absorb impact force during ballistic activities such as jumping.1,2 Limited ankle joint dorsiflexion is commonly caused by tightness of soleus and gastrocnemius muscles,3,4 and has been shown to be a risk factor for and/or associated with several musculoskeletal pathologies of the foot including forefoot pain,3 plantar fasciitis5 and navicular stress fractures.6 Patella7 and Achilles tendinopathy,8 ankle sprains9 and lower limb overuse injuries in football players10 have also been shown to be caused by, or associated with limited ankle joint dorsiflexion. It is therefore important that clinicians who manage musculoskeletal pathology of the foot and lower limb are able to reliably assess ankle joint dorsiflexion range of motion. This would allow the practitioner to identify those at risk of developing foot and lower limb injuries, accurately measure the level of dysfunction post-injury and determine the effectiveness of an intervention aimed at improving ankle joint dorsiflexion range of motion. The measurement of ankle joint dorsiflexion has traditionally occurred with the patient in a non-weightbearing position.4 However, the reliability of this measurement technique is questionable (intra-rater reliability ICCs ranging from 0.64 to 0.99 and inter-rater ICCs ranging from 0.29 to 0.81).11 In light of the questionable reliability of non-weightbearing measurements of ankle joint dorsiflexion, an alternative weightbearing ‘lunge’ technique has been described.12 This measurement technique has been shown to be reliable (high intraand inter-rater reliability).12,13 However, a major limitation of this measurement technique is that it primarily assesses the role of the soleus muscle and joint capsule structures of the ankle joint as it is performed with a flexed knee.4 This measurement technique is unable to determine if tightness of the gastrocnemius muscle is a contributing factor to limited ankle joint dorsiflexion.4 One way to overcome this limitation would be to perform the measurement of ankle joint dorsiflexion range of motion in a weightbearing position with the knee extended. Only one study has investigated the reliability of the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended.14 Although the results showed high intrarater reliability (coefficient of variation of 2.5%), the inter-rater reliability was not reported. Furthermore, only experienced clinicians were used, so it is unknown if this measurement technique is reliable when inexperienced raters perform this measurement. Therefore, the aim of this study was to determine both the intra- and inter-rater reliability of
55 the measurement of ankle dorsiflexion in a weightbearing position with the knee extended, using both experienced and inexperienced raters.
Methods Participants Participants were recruited from a student population at a University. Thirty individuals (10 male, 20 female), aged 19—42 years (mean ± S.D., 22.1 ± 5.6), height (mean ± S.D.) 171.8 ± 8.9 cm, BMI (mean ± S.D.) 22.8 ± 3.3 were recruited. Participants were excluded if they had any acute or chronic lower limb pathology in the previous 12 months, previous history of surgery to the lower limbs or any neurological or balance deficits. Institutional ethics approval was granted prior to the study and all participants provided written informed consent.
Raters Four podiatrists were used as raters. Raters A—C had 3, 10 and 20 years of clinical experience, respectively. Rater D was a fourth year undergraduate podiatry student, considered to have minimal clinical experience. Prior to commencing data collection, all raters undertook two 15 min training sessions which allowed the raters to familiarise themselves with the measurement protocol and practice the measurement technique. The training sessions were separated by 3 days and the final session occurred 1 week prior to data collection.
Measurement technique The participant placed both hands on a wall in front of them. They positioned their right leg behind the left leg as far as possible ensuring the right knee was fully extended. The right foot was positioned parallel to a tape-line on the floor, which was orientated perpendicular to the wall. The second toe and the centre of the heel were placed directly over the tape-line in order to attempt to reduce the subtalar joint from pronating during the measurement procedure and therefore falsely elevating the value of ankle joint dorsiflexion.9 The participant then leaned forward until maximum stretch was felt in the right posterior leg, while keeping the right knee fully extended and the right heel in contact with the ground. The left leg remained in a comfortable position to maintain balance and not to restrict dorsiflexion of the right ankle. The angle
56 the right tibia made to the vertical was then measured using (i) a digital inclinometer and (ii) a clear acrylic plate apparatus. Digital inclinometer The rater aligned the digital inclinometer (Baseline® Digital Inclinometer 12-1057) so that it was positioned on a mark made on the mid-point of the anterior tibial border, between the tibial tuberosity and the anterior joint line of the ankle. Care was taken to ensure that the digital inclinometer was not positioned over the tibialis anterior muscle belly. To minimise rater bias, the face of the digital inclinometer was positioned away from the rater and the readings were recorded (in degrees) by an independent third person (Supplementary File 1). Clear acrylic plate apparatus A clear acrylic plate apparatus marked with 2◦ increments was used to measure ankle joint dorsiflexion.13 For each participant, two anatomical points were marked. Firstly, the lateral malleolus was identified and marked, being the axis of rotation of the ankle joint. Secondly, the head of the fibula was located and marked as the proximal landmark.13 The rater then positioned the clear acrylic plate apparatus perpendicular to the wall alongside the participant, ensuring the marking (on the bottom right corner) of the clear acrylic plate apparatus was bisecting the lateral malleolus. The participant then leaned forward and the position of the fibula head was marked on the clear acrylic plate apparatus with a nonpermanent marker (Supplementary File 2). The angle formed between the lateral malleolus and the fibula head relative to the vertical was recorded (in degrees) by an independent third person, who then removed the marking on the clear acrylic plate apparatus.
Procedure Participants initially sat for 5 min and then completed a series of pre-conditioning stretches of the gastrocnemius muscle prior to data collection.15,16 Each participant performed three, 30 s gastrocnemius muscle stretches of the right leg with a 10 s rest period between each stretch to pre-condition the gastrocnemius muscle as well as familiarise themselves with the measurement technique.16 After this pre-conditioning procedure, data collection began. The participant lay supine while the rater marked the anatomical landmarks on the participant’s right leg using a non-permanent
S.E. Munteanu et al. ink marker. Three anatomical landmarks were marked, the fibula head, the lateral malleolus13 and the mid-point of the anterior border of the tibia.12 The participants then assumed the extended knee weightbearing position described previously. The angle that the tibia made to the vertical was measured using (i) a digital inclinometer and (ii) the clear acrylic plate apparatus. The participant returned to the starting position to rest for 10 s and the measurement was repeated. The mean value of the two measurements for each measurement apparatus was documented and used for data analysis.13 Once the measurement procedure was performed by each rater, the ink markings were removed using alcohol wipes. The four raters each performed the measurement procedure within a 20 min period. The sequence of raters was randomised for both the test and retest sessions, as was the order of measurement apparatus used. Each participant returned after 7 days and the measurement protocol was repeated. A 1-week test—retest period was used as this testing interval was considered large enough to avoid fatigue, learning and memory effects, but small enough to avoid genuine changes in ankle joint range of motion.12
Statistical analysis Data from the right side only was used to satisfy the assumption of independence of data.17 Data was explored for normal distribution (Shapiro—Wilks test). A two-way repeated measures ANOVA was used to assess for systematic differences between repeated measures for each rater (two levels: test and retest sessions) and between raters (four levels: raters A—D). P-values less than 0.05 were considered significant. Post hoc comparisons were performed using Bonferroni-adjusted paired t-tests.18 To determine the intra-rater reliability for each rater, two approaches were used: intraclass correlation coefficients (ICCs) were calculated (model 2,2), as were standard error of measurement (S.E.M.) with 95% limits of agreement (95% LOAs).19 To determine the average intra-rater ICC for raters A—C (experienced clinicians); a form of standardised (z) score was used. Individual raters’ ICC (r) values were transformed to z-scores. The resulting z-scores were averaged and the average z-score was then transformed back into an r value.20 To determine the inter-rater reliability, ICCs (model 2,4) and mean S.E.M.s with 95% LOAs were calculated.21 A mean inter-rater 95% LOA was
Measurement of ankle dorsiflexion is reliable
57
derived from the average of the combinations of comparisons of raters A—D. Data from both the test and retest sessions were analysed.
Results Ankle joint dorsiflexion measured with a digital inclinometer The mean (range) values for each rater at the test and retest sessions are shown in Supplementary File 3. The main effect of session was not significant (F1 = 2.992, p = 0.09). Similarly, the main effect of rater was not significant (F3 = 2.470, p = 0.07). Clinically, these results suggest error associated with measurement between raters and between sessions was random and not a result of systematic differences. Intra- and inter-rater reliability of the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended is shown in Table 1. All three experienced raters (A—C) demonstrated high intra-rater reliability with ICCs between 0.85 and 0.91 and narrow 95% LOAs. The inexperienced rater (rater D) showed slightly less reliability with a lower ICC and wider 95% LOA. Table 1 also shows the ICCs (95% CI), S.E.M.s and 95% LOAs for the inter-rater reliability of both the test and retest sessions for all four raters. The reliability values for the test session were slightly greater than the retest session. However, the inter-rater reliability for both sessions was high, indicated by ICCs greater than 0.90 and narrow 95% LOAs.
Ankle joint dorsiflexion measured with a clear acrylic plate apparatus The mean ± S.D. (range) values for each rater at the test and retest session are shown in Supplementary File 3. The main effect of rater was not significant (F3 = 2.013, p = 0.12). However, the main effect of session was significant (F1 = 16.476, p < 0.001) revealing significant differences between the test and retest sessions for all raters except rater B. Intra- and inter-rater reliability of the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended using the clear acrylic plate apparatus is shown in Table 2. All raters, except rater B demonstrated high intrarater reliability with ICCs between 0.89 and 0.96 and narrow 95% LOAs. Rater B showed moderate reliability with ICCs considerably lower and 95% LOAs considerably wider than the other three raters (A, C and D). Table 2 also shows the ICCs (95% CI), S.E.M.s and 95% LOAs for the inter-rater reliability for the test and retest sessions of all four raters. The inter-rater reliability for both the test and retest sessions was high, with ICCs greater than 0.92 and narrow 95% LOAs.
Discussion This study has demonstrated that measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended can be performed reliably by experienced and inexperienced raters using both
Table 1 The intra- and inter-rater reliability for the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended using a digital inclinometer
Table 2 The intra- and inter-rater reliability for the measurement of ankle joint dorsiflexion in a weightbearing position with the knee extended using a clear acrylic plate apparatus
Rater
Rater
A B C Averagea D
Intra-rater reliability Type (2,2) ICC (95% CI)
S.E.M. (95% LOA) (◦ )
0.87 0.85 0.91 0.88 0.77
1.6 1.8 1.2 1.5 2.4
(0.72—0.94) (0.69—0.93) (0.81—0.96) (0.75—0.94) (0.52—0.89)
(−6.5 (−7.7 (−5.5 (−6.6 (−9.1
to to to to to
5.5) 5.6) 3.4) 4.8) 8.3)
A B C Averagea D
Inter-rater reliability Type (2,4) ICC S.E.M. (95% LOA) (95% CI) (◦ ) Test Retest a
0.95 (0.91—0.97) 0.92 (0.86—0.96)
z-Transformed data.
1.77 (−5.7 to 5.7) 2.05 (−6.3 to 6.3)
Intra-rater reliability Type (2,2) ICC (95% CI)
S.E.M. (95% LOA) (◦ )
0.96 0.67 0.90 0.89 0.89
1.0 2.5 1.3 1.6 1.7
(0.91—0.98) (0.34—0.85) (0.79—0.95) (0.76—0.95) (0.77—0.94)
(−5.2 to 2.4) (−10.0 to 7.3) (−6.5 to 3.1) (−7.2 to 4.3) (−8.1 to 4.6)
Inter-rater reliability Type (2,4) ICC S.E.M. (95% LOA) (95% CI) (◦ ) Test Retest a
0.97 (0.95—0.98) 0.93 (0.87—0.96)
z-Transformed data.
1.3 (−4.7 to 4.7) 1.8 (−6.2 to 6.2)
58 the digital inclinometer and the clear acrylic plate apparatus. These results are comparable to the findings from the study by Ekstrand et al.14 However, our study adds to the work of Ekstrand et al.14 as they assessed intra-rater reliability only and used experienced raters only. An issue to consider when interpreting the results of the present study was that one experienced rater showed considerably lower intra-rater reliability than the other raters when measuring ankle joint dorsiflexion using the clear acrylic plate apparatus. This technique (more so than the digital inclinometer) relies on the ability of the rater to palpate surface anatomical landmarks (such as the fibula head). Imprecision in locating and marking relevant anatomical locations could adversely affect the reliability of this technique. In order to interpret the reliability findings in a clinical context, 95% LOAs were determined.21 The 95% LOAs suggest that to attribute a difference in ankle joint dorsiflexion to a ‘true change/difference’ and not measurement error, the observed change/difference must be greater than 7◦ and 6◦ when performed by the same rater or different raters, respectively. Therefore, this measurement technique would be appropriate to use as a screening tool to determine those at risk of developing lower limb injuries, as there is a large range of ankle joint dorsiflexion values in the population (34◦ —60◦ ) and these differences do affect the risk of being injured.9 In contrast, this measurement technique may be inappropriate when used to assess for changes in ankle joint dorsiflexion range of motion resulting from a calf muscle stretching program in young, healthy people as only small changes in range of motion (∼2◦ —3◦ ) are expected.22 Although, the technique may be a useful outcome measure for stretching interventions in other clinical groups (such as older people or those with heel pain) where larger increases in ankle range of motion may be achieved.23,24 The results of this study need to be interpreted in the context of its limitations. One limitation of weightbearing measurements of ankle joint dorsiflexion is that they are unlikely to be a true measure of dorsiflexion occurring solely at the ankle joint but instead, provide a cumulative measure of motion available at the talocrural, subtalar and tarsal joints.12 Indeed, a more pronated foot posture has been shown to be positively correlated to the ankle joint weightbearing lunge.25 In addition, the findings regarding the inexperienced rater need to be interpreted with caution since only one inexperienced rater was used which makes it difficult to make generalised comments about inexperienced raters. Finally, the results of this study
S.E. Munteanu et al. cannot be extrapolated to patients with lower limb pathology or those outside the age range of 18—42 years. As health practitioners are more likely to treat symptomatic individuals of all ages, further research needs to be done to determine the reliability of the weightbearing measurement of ankle joint dorsiflexion with the knee extended in these populations.
Practical implications • Measurements of ankle joint dorsiflexion with participants in a weightbearing position with the knee extended are reliable when performed by the same rater or by different raters. • The reliability of measurements of ankle joint dorsiflexion are not strongly affected by the experience of the rater or the equipment used.
Supplementary Files Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jsams.2007.06.009.
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